MRTG is a very popular open source tool for server statistics. Wether you use it for traffic, CPU load, or whatever.

This package is part of standard tools for CentOS. Same counts for Perl, SNMP, etcetera.
Whenever you decide to use an additional repository for server maintenance, e.g. The Atomic Rocket Turtle repo, then you might run into some problems these days.

The rocket turtle has released an update for Perl-IO-Socket-INET6, which is used in MRTG. This might bring some problems like following:

Depending on how often your CRON job is configured for running web statistics MRTG, you may receive following error:

Subroutine SNMPv1_Session::AF_INET6 redefined at /usr/lib/perl5/5.8.8/Exporter.pm line 65.
at /usr/bin/../lib64/mrtg2/SNMP_Session.pm line 594
Subroutine main::AF_INET6 redefined at /usr/lib/perl5/5.8.8/Exporter.pm line 65.
at /usr/bin/mrtg line 97

This already is an old bug in MRTG: http://oss.oetiker.ch/mrtg-trac/ticket/45
There are several ways to fix this, like re-installing Perl, roll back your update (if you configured that).
I choose following fix:

Edit: /usr/bin/mrtg

Then find “import Socket6″ (note: without the “;") and replace it with:

On a single domain controller, configure the SYSVOL replica set to be authoritative. This reference domain controller will contain the authoritative copy of the SYSVOL tree for all other members of the replica set. For example, other domain controllers in the domain will directly or transitively replicate from this reference domain controller.

Choose the reference domain controller based on connectivity and physical server resources. This domain controller will be known as the “reference domain controller" in all subsequent steps.

To configure the SYSVOL replica set to be authoritative, follow these steps:
Click Start, click Run, type regedit, and then click OK.
Locate and then click the BurFlags entry under the following registry subkey:HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\NtFrs\Parameters\Cumulative Replica Sets\GUID
GUID is the GUID of the domain system volume replica set that is shown in the following registry subkey:HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\NtFrs\Parameters\Replica Sets\GUID
Right-click BurFlags, and then click Modify.
Type D4 in the Value Data field (HexaDecimal), and then click OK.